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Re: Hyperchloraemic acidosis in patients given rapid isotonic saline infusions

Dear Editor,

Holliday et al. suggested that rehydration in hypovolaemic children with acute gastroenteritis should be by rapid infusion of isotonic saline (1). The authors refer to studies demonstrating a faster return of antidiuretic hormone (ADH) levels to normal as a marker for restoration of intravascular volume in children receiving rapid intravascular volume expansion. The authors also mention that ADH secretion in children with gastroenteritis is stimulated by nausea and vomiting. Nausea and vomiting is fuelled by starvation ketosis (2) in dehydrated children with gastroenteritis. The rapid application of isotonic saline causes in addition to the gastroenteritis induced acidosis predictably a significant hyperchloraemic acidosis by reduction of the strong anion gap (3). The induction of hyperchloraemic acidosis has been demonstrated in double blind randomised controlled trials of patients receiving rapid isotonic saline infusions as volume replacement during operations in theatre (4). The resulting hyperchloraemic acidosis can reduce gastric perfusion and glomerular filtration rate (5) and prompt the administration of unnecessary additional fluid boluses by physicians who may think the metabolic acidosis is caused by hypovolaemia. Isotonic saline infusion is also unable to switch off ketogenesis leaving the patient exposed to nauseating amounts of ketone bodies. Glucose application is essential in reduction of ketone bodies by stimulation of insulin secretion switching off ketogenesis (6). The authors also seem to advocate isotonic saline as maintenance treatment intraoperatively. This is potentially dangerous in young and particularly in preterm infants in the neonatal period, who are prone to hypoglycaemia in the absence of a constant supply of glucose. Future research should not include isotonic saline infusions with its known adverse effects but replace them by balanced electrolyte solutions like Hartmanns solution, which can avoid chloride overload while providing adequate amounts of sodium. Maintenance fluid needs to contain glucose which can reduce ketosis and prevent hypoglycemia.

There are no competing interests to declare.

References:

1. Holliday MA, Ray PE, Friedman AL. Fluid therapy for children: Facts, fashions and questions. Arch Dis Child 2007 [Epub ahead of print].

2. Kang HC, Chung DE, Kim DW, Kim HD. Early-and late-onset complications of the ketogenic diet for intractable epilepsy. Epilepsia 2004;45:1116-23.

3. Prough DS, Bidani A. Hyperchloremic metabolic acidosis is a predictable consequence of intraoperative infusion of 0.9% saline. Anesthesiology 1999;90:1247-9.

4. Eisenhut M. Adverse effects of rapid isotonic saline infusion. Arch Dis Child 2006; 91:797.

5. Bullivant EMA, Wilcox CS, Welch WJ. Intrarenal vasoconstriction during hyperchloremia: role of thromboxane. Am J Physiol 1989; 256:152-7.